Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[tsutsuji]

http://www3.nhk.or.jp/news/genpatsu-fukushima/20120201/index.html An 8.5 ton leak was found on unit 4's first floor at 10:30 PM on 31 January. A ⌀ 9mm pipe connected to the reactor was pulled out of a junction part. The radiation of the water is 35.5 Bq/cm³ . The leak was stopped by closing a valve on the reactor side. The water went no further than the reactor building basement. Tepco said "we are unsure if this was caused by frost".

http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_120201_01-e.pdf "Status of Water Leakage on the 1st floor of Unit 4 Reactor Building, Fukushima Daiichi Nuclear Power Station (Test line of the Piping for Jet Pump Measurement)"

http://www.47news.jp/CN/201202/CN2012020101002248.html It is thought that the water started leaking at around 5 PM on 30 January. Tepco earlier reported a 6 liter leak, but after checking, announced the quantity was 8.5 tons. The 8.5 ton quantity is inferred from the water level drop in the tank installed on the side of the fuel pool. It is thought that the water expanded by freezing, creating an internal pressure pushing the pipe away.

In the afternoon press conference, Junichi Matsumoto makes a small drawing on the white board and explains to a journalist that the fuel pool's water level remained stable, even though the skimmer surge tank's water level decreased on 30 January by 60 to 90 mm/hour (instead of the usual 3 mm/hour caused by evaporation). Tepco started patrolling the plant to find the leak at 22:00 on 31 January. Junichi Matsumoto agrees with a journalist that this was late, but as the airfin cooler had been adjusted, the operators thought that the water level drop could have resulted of a drop of temperature, and hoped for about 24 hours that the water level would stabilize. When the leak was stopped, the skimmer surge tank water level had dropped by 1.10 m (1 February afternoon press conference video at http://www.tepco.co.jp/tepconews/library/movie-01j.html )

http://www.tepco.co.jp/en/nu/fukushima-np/f1/images/intake_canal_120201-e.pdf page 3 "There was no Pu-238, Pu-239 and Pu-240 detected from the sample for this analysis" [north water intake canal Units 1-4 Fukushima Daiichi Nuclear Power Station, 16 January]

http://www.tepco.co.jp/en/nu/fukushima-np/f1/images/soil_120201-e.pdf "Radioactive density of the Pu-239 and Pu-240 detected on January 16 was within the same level as that of fallout of past nuclear test in the atmosphere." [soil]

http://www.tepco.co.jp/en/nu/fukushima-np/f1/images/kakuhou_120201-e.pdf page 145/148 : 3.1E-05 Bq/cm³ of Ag-110m in the air at Upper part of reactor building of Unit 3 on 6 January

http://www.tepco.co.jp/en/nu/fukushima-np/f1/images/kakuhou_120201-e.pdf page 115/148 : 5.3 E-02 Bq/cm³ of Ru-106 in unit 3 subdrain on 11 January. (Ru-106 had been previously found in soil and dust samples in March, Junichi Matsumoto says in the 1 February afternoon press conference video at http://www.tepco.co.jp/tepconews/library/movie-01j.html )

http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_120201_03-e.pdf "Measures against Freeze of Water Treatment Facility / Measures against Freeze of Reactor Water Injection System at Fukushima Daiichi Nuclear Power Station" ["floodlight", on page 3, is a well coined English word]

http://mainichi.jp/select/jiken/news/20120202k0000m040080000c.html Tepco found 158 mistakes in the stress test report sent to NISA for Kashiwazaki Kariwa units 1 to 7. These are simple mistakes without consequences on the report's conclusions.

http://www.tepco.co.jp/cc/press/betu12_j/images/120131g.pdf Attachment 7 page 24/46 mentions a "water-hammer effect".

what equipment is that fractured pipe?

No pipe was fractured. Only a packing was deformed, as you can see on the photographs on attachment 6 page 23/46. The blue equipment (pink equipment on the diagram on attachment 7) is a preheater belonging to an evaporative concentration apparatus.

The contrived headline to confuse some theoretical quake with the actual event and the breathless recounting of forces to theoretical pipes under those imagined conditions misses the opportunity to actually inform us about the condition of the real structures at reactor #5. Based on past experience, if there was anything actually wrong, that would have been described in the most dramatic terms possible, so I'll assume, for now, that the structures at unit 5 are in reasonably good shape.

I tried to have a look at what was said about unit 5's earthquake resistance in the second report to IAEA.

On http://www.iaea.org/newscenter/focus/fukushima/japan-report2/chapter-2-1.pdf (English) page II-49 there is a "Table II-2-6 Overview of Impact Evaluation on Equipment and Piping Systems important for Seismic Safety (Fukushima Dai-ichi NPS, Unit 5)" with two columns with figures. The left column is the standard earthquake ground motion Ss, and the right column is the simulation result. Some of the figures in the right column are a few percent higher than those in the left column. Is it dangerous ? There is also a small peak on one of the plots on the same page marked with "peak considered to be generated according to the simulation analysis" and I am unsure what this means.

 

[Joffan]

Thanks tsutsuji, great reference. Those tables are discussed very briefly on p II-42/3:

Based on the comparison results, according to TEPCO, it was found that for Units 1 to 3, and 5, some of those indexes such as seismic load by the earthquake exceeded the ones from the seismic safety assessment. However, a seismic assessment of major components that have important safety functions relevant to "Shutdown" and "Cool down" of reactors, and "Containment" of radioactive materials was performed, and found that the calculated stress, etc. were below the criteria (Tables II-2-2 to II-2-7). For Units 4 and 6, it was found that those indexes such as seismic load by the earthquake, except some peak floor response spectra, were below the ones from the seismic safety assessment.
And also, a seismic assessment of the piping systems using floor response spectra was performed, for Units 1 to 6, and found that the calculated stress was below the criteria (Tables II-2-8 to II-2-13).

 

[jim hardy]

"""No pipe was fractured. Only a packing was deformed, as you can see on the photographs on attachment 6 page 23/46. The blue equipment (pink equipment on the diagram on attachment 7) is a preheater belonging to an evaporative concentration apparatus."'

THANKS, Tsujitsu !

i should have looked further...

 

[tsutsuji]

http://www3.nhk.or.jp/news/genpatsu-fukushima/20120204/index.html On 3 February, a leak smaller than 1 liter was found at a tank containing high strontium concentration. The gamma ray at the surface of the water is 22 mSv/hour and the beta ray is 2000 mSv/hour. The leak was stopped by tightening a bolt. This is the same sort of leak as on 10 January ( https://www.physicsforums.com/showpost.php?p=3704022&postcount=12136 ). As there are about 100 such tanks, the NISA ordered Tepco to check them and to take countermeasures. Tecpo is investigating, thinking that as the tanks were urgently built, they were assembled with bolts instead of welding.

http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_120203_04-e.pdf "Leakage from water desalinations(RO)concentrated water tank" 3 February

http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_120110_03-e.pdf "Water leakage from the concentrated water tank of the water desalinations (reverse osmosis membrane)" 10 January

http://www3.nhk.or.jp/news/genpatsu-fukushima/20120203/index.html The NISA will conduct its first inspection at Fukushima Daiichi since the accident for 3 weeks starting on 6 February. During that period, the status of the inspection will be released to the media.

http://www.jiji.com/jc/c?g=soc_30&k=2012020300467 On 3 February, Tepco said that the water level in unit 4's skimmer surge tank was decreasing at twice the usual pace and that there is a high probability that the water is leaking. Tepco is urgently looking for the location of the leak.

 

[Martin Peters]

Tepco has posted an English document describing the work they did to reduce the level of radiation in a parking lot: "Radiation dose reduction by collecting dust and small rubbles
at the parking lot in front of Main Anti-Earthquake Building of Fukushima Daiichi Nuclear Power Station"

http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_120203_01-e.pdf

The maximum value of radiation at 1 cm above the surface (shown below the lower left chart) appears to be erroneous. According to the color key, the red dots in the chart show locations where the surface radiation was >1000 µSv/hr. Since a comma appears to the left of the digits "240", I suspect that a digit to its left has been lost.

Edit at 0300 UT, 4 Feb 2012: The Japanese version of this doc shows that the value is 1,240 µSv/hr.

 

[tsutsuji]

http://www.jiji.com/jc/c?g=soc_30&k=2012020300467 On 3 February, Tepco said that the water level in unit 4's skimmer surge tank was decreasing at twice the usual pace and that there is a high probability that the water is leaking. Tepco is urgently looking for the location of the leak.

The above is dated 2012/02/03-12:54 so it is probably from the morning press conference. I watched the 3 February afternoon press conference video ( http://www.tepco.co.jp/tepconews/library/movie-01j.html ), where Junichi Matsumoto said that after refilling the skimmer surge tank, the dropping rate was around 10 mm/hour which is within the allowed range, taking evaporation into consideration.

I checked the skimmer surge tank water level data at
http://www.tepco.co.jp/en/nu/fukushima-np/f1/images/12020406_table_summary-e.pdf
http://www.tepco.co.jp/en/nu/fukushima-np/f1/images/12020312_table_summary-e.pdf
http://www.tepco.co.jp/en/nu/fukushima-np/f1/images/12011712_table_summary-e.pdf
http://www.tepco.co.jp/en/nu/fukushima-np/f1/images/12011812_table_summary-e.pdf

2997mm on 4 February 05:00
3179mm on 3 February 11:00
(3179-2997)/(24+5-11)=10.1 mm/hour

2318mm on 18 January 11:00
2388mm on 17 January 11:00
(2388-2318)/24 = 2.92 mm/hour

I don't understand why they refilled so little on 3 February (to perhaps between 3000 and 4000 mm, instead of refilling to more than 5000 mm)

In the 4 February afternoon press conference video ( http://www.tepco.co.jp/tepconews/library/movie-01j.html ), Tetsuya Terasawa says that they measured 4 mm between 6:28 and 6:53 in the morning which he calls "a stable 4 mm". He says they reached the conclusion that the variation of skimmer surge tank water level is explained by causes such as evaporation and the volume variation caused by temperature, and is not caused by a leak. The NHK journalist asked if it is 4 mm "per hour", and Terasawa said "yes" (until the NHK journalist asked, I thought it was 4 mm in the 25 minutes from 6:28 to 6:53). He also said that there was a 12 mm/hour drop at 11:00 on 3 February. Tepco has no plan to further investigate the causes of the water level drop, but will carefully survey the skimmer surge tank water level.

http://www.asahi.com/national/jiji/JJT201202040074.html [4 February 22:06] Tepco was studying the possibility of a leak as unit 4's skimmer surge tank water level was decreasing at twice the usual pace on 1 and 2 February, but after refilling the tank, the decrease rate became smaller. Tepco explains the temporarily quick pace with the reduction of volume due to the temperature fall and to the evaporation increase due to dry air.

 

[elektrownik]

I found top floor of unit 4 map:
http://twitter.com/#!/minorucchu/status/164533275312926720/photo/1/large

 

[MJRacer]

Elevation of Emergency Diesel Generators (EDG) at Fukushima Dai-Ichi
(O.P.: Onahama port base tide level for construction, page II-68 of http://www.iaea.org/newscenter/focus/fukushima/japan-report2/chapter-2-1.pdf (the second report to the IAEA linked by tsutsuji)):

From Table II-2-14 on page II-72:

Unit 1
A: O.P. +4.9m (Flooded)
B: O.P. +0.2m (Flooded)

Unit 2
A: O.P. +1.9m (Flooded)
B: O.P. +10.2m (Not Flooded)

Unit 3
A: O.P. +1.9m (Flooded)
B: O.P. +1.9m (Flooded)

Unit 4
A: O.P. +1.9m (Flooded, but out of service due to repair)
B: O.P. +10.2m (Not-Flooded)

Unit 5
A: O.P. +4.9m (Not-Flooded)
B: O.P. +4.9m (Not-Flooded)

Unit 6
A: O.P. +5.8m (Not-Flooded)
B: O.P. +13.2m (Not-Flooded)
C: O.P. +5.8m (Not-Flooded)

EDGs 2B, 4B, 5A&B and 6A&H were not flooded but were "unusable due to inundated main/ancillary equipment."

All of the power distribution panels were flooded, except that none of the panels in Unit 6 were and the DC main bus panels only in Units 3 and 5 weren't either.

Elevation of DC main bus panels:
Unit 1: O.P. +4.9m
Unit 2: O.P. +1.9m
Unit 3: O.P. +6.5m
Unit 4: O.P. +1.9m
Unit 5: O.P. +9.5m
Unit 6: O.P. +9.5m

Tsunami level: O.P.+14~16m (Figure II-2-20,page II-73)
Units 1-4 Ground level: O.P.+10m
Units 5&6 Ground level: O.P.+13m

The only usable diesel generator (Unit 6B) was apparently in a separate building (the Diesel Generator Building). (See Figure II-2-25, page II-77 for location of building and inset in Figure II_2-20, page II-73 for schematic showing elevation.)

Otherwise, Units 5 and 6 might have been lost also.

 

[tsutsuji]

http://www3.nhk.or.jp/news/genpatsu-fukushima/20120206/index.html One of unit 2's thermometers is rising. It displayed 45°C on 27 January, and it has been gradually rising since then, reaching 71.7°C a 04:00 PM on 5 February. At 1:30 AM on 6 February, the water injection rate was raised by 1 ton/hour to 10.6 tons/hour, but at 07:00 AM, the thermometer displayed 73.3°C. The other two PCV bottom thermometers are remaining stable at 44°C. Tepco says there is a possibility that the water flow changed when the injection was restarted after a temporary suspension on 26 January that was necessary for some works.

 

[elektrownik]

http://www3.nhk.or.jp/news/genpatsu-fukushima/20120206/index.html One of unit 2's thermometers is rising. It displayed 45°C on 27 January, and it has been gradually rising since then, reaching 71.7°C a 04:00 PM on 5 February. At 1:30 AM on 6 February, the water injection rate was raised by 1 ton/hour to 10.6 tons/hour, but at 07:00 AM, the thermometer displayed 73.3°C. The other two PCV bottom thermometers are remaining stable at 44°C. Tepco says there is a possibility that the water flow changed when the injection was restarted after a temporary suspension on 26 January that was necessary for some works.

And from tepco press conference:
"Tepco announced they are going to add 960 Kg of boric acid tonight in JST."

 

[tsutsuji]

http://www3.nhk.or.jp/news/html/20120206/t10015820341000.html Unit 2 thermometer : 71°C at 11 AM, and 69.2 at 5 PM on 6 February. Tepco plans to further increase the water injection rate by 3 tons/hour in the night of 6 February. Judging from xenon concentrations, Tepco says no recriticality is occurring.

http://www3.nhk.or.jp/news/genpatsu-fukushima/20120206/1915_senmonka.html Hiroaki Suzuki of the Institute of Applied Energy mentions two possible causes : the water flow changed after injection was restarted in January, or a piece of fuel fell down from above to a location close to the thermometer.

http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_120206_02-e.pdf the data of the three RPV bottom thermometers

 

[zapperzero]

And from tepco press conference:
"Tepco announced they are going to add 960 Kg of boric acid tonight in JST."

Well, well. The plot thickens. So, if they do it and the temperature change is reversed, we could then conclude re-criticality?

 

[elektrownik]

del this

 

[tsutsuji]

http://sankei.jp.msn.com/science/news/120207/scn12020701100002-n1.htm Boric acid injection was started in the early morning of 7 February.

 

[jmelson]

And from tepco press conference:
"Tepco announced they are going to add 960 Kg of boric acid tonight in JST."

Oh MAN! This is a scary development! And, in the reactor whose condition we seem to know the least about.

Jon

 

[jmelson]

http://www3.nhk.or.jp/news/html/20120206/t10015820341000.html Unit 2 thermometer : 71°C at 11 AM, and 69.2 at 5 PM on 6 February. Tepco plans to further increase the water injection rate by 3 tons/hour in the night of 6 February. Judging from xenon concentrations, Tepco says no recriticality is occurring.

If there's no recriticality, why the HELL are they adding boric acid?

Jon

 

[Cire]

If there's no recriticality, why the HELL are they adding boric acid?

Jon

It's called being proactive instead of being reactive.

 

[Borek]

Truth is, for some people whatever they do, they do wrong.

If they add boric acid, it means they are adding it because they know there is a recriticality, they just doesn't tell anyone. If they don't add boric acid, why the hell they don't add this if there is an obvious recriticality? It is their fault both ways.

 

[tsutsuji]

http://www.bloomberg.co.jp/news/123-LYZRMA6JTSE801.html Boric acid was added from 00:19 to 03:20 AM on 7 February. The core spray system injection rate was increased nearly two-fold from 04:24 AM. Temperatures:

6 February 17:00 : 69.2°C
6 February 23:00 : 69.9°C
7 February 05:00 : 72.2°C
7 February 07:00 : 70.1°C

 

[mheslep]

Truth is, for some people whatever they do, they do wrong.

If they add boric acid, it means they are adding it because they know there is a recriticality, they just doesn't tell anyone. If they don't add boric acid, why the hell they don't add this if there is an obvious recriticality? It is their fault both ways.

Sshhh. You could put the internet out of business.

 

[jim hardy]

duh,,,

if you've been adding water you're diluting the boric acid that you put in there a while ago.
better toss in a few spoonfuls now and then .

 

[joewein]

The only usable diesel generator (Unit 6B) was apparently in a separate building (the Diesel Generator Building). (See Figure II-2-25, page II-77 for location of building and inset in Figure II_2-20, page II-73 for schematic showing elevation.)

Otherwise, Units 5 and 6 might have been lost also.

The difference was that this one was air-cooled. So when the cooling water intake was knocked out, the other EDGs in units 5 and 6 became unusable despite not being flooded, but this could keep going and save the day.

 

[MJRacer]

The difference was that this one was air-cooled. So when the cooling water intake was knocked out, the other EDGs in units 5 and 6 became unusable despite not being flooded, but this could keep going and save the day.

True.

From pages 20 and 21 of http://www.iaea.org/inisnkm/nkm/pages/2011/NEMschool2011/topics/topic0/Fukushima Overview_Sekimura.pdf (Overview of the Accident in Fukushima Daiichi Power Plants by Naoto Sekimura).

Unit 2
B: O.P. +10.2m (Not Flooded)(Air-Cooled)

Unit 4
B: O.P. +10.2m (Not-Flooded)(Air-Cooled)

Unit 6
B: O.P. +13.2m (Not-Flooded)(Air-Cooled)

So, 3 EDGs were air-cooled and not-flooded. If one EDG was able to save Units 5 and 6, maybe the EDG in Unit 2 could have saved Units 1 and 2 and the EDG in Unit 4 could have saved Units 3 and 4. However, the electrical panels in Units 2 and 4 were flooded. Also, IIRC, one seawater pump was saved (Unit 6) and a submersible pump was improvised to save Unit 5. I don't think any of the seawater pumps for Units 1 and 4 were saved, but don't quote me on that.

 

[swl]

Truth is, for some people whatever they do, they do wrong.

If they add boric acid, it means they are adding it because they know there is a recriticality, they just doesn't tell anyone. If they don't add boric acid, why the hell they don't add this if there is an obvious recriticality? It is their fault both ways.

Sounds like they are doing the right thing in this case. The temperature rose, they checked the reactor gasses, and now they have responded by injecting boric acid. I would be interested to learn what isotopes were detected in the gas analysis.

 

[zapperzero]

Truth is, for some people whatever they do, they do wrong.

If they add boric acid, it means they are adding it because they know there is a recriticality, they just doesn't tell anyone. If they don't add boric acid, why the hell they don't add this if there is an obvious recriticality? It is their fault both ways.

You know... the only thing that bothers me about the same is the equal and opposite reaction from those (not you, obviously) who want to believe there is no possibility of anything going wrong.

"Doubling the core spray volume and adding boric acid? An excess of precaution. Nothing to see here, move along."

But there is something to see. That thermo-couple is working just fine, we just don't know what's heating it up. I asked the question about recriticality not because I like tragedies, but because I really wanted to know what you guys think!

Evidently, I was not the only one to ask that question, as TEPCO has been checking for xenon (a fact of which I was unaware at the time):

http://www.businessweek.com/news/2012-02-07/tepco-injects-boric-acid-into-reactor-as-temperatures-rise.html

 

[tsutsuji]

http://www.bloomberg.co.jp/news/123-LYZRMA6JTSE801.html Boric acid was added from 00:19 to 03:20 AM on 7 February. The core spray system injection rate was increased nearly two-fold from 04:24 AM. Temperatures:

6 February 17:00 : 69.2°C
6 February 23:00 : 69.9°C
7 February 05:00 : 72.2°C
7 February 07:00 : 70.1°C

http://www3.nhk.or.jp/news/genpatsu-fukushima/20120207/index.html The core spray system flow rate was increased by 3 tons/hour at around 4 AM on 7 February. Total flow rate: 13.5 tons/hour. Tepco is surveying with deep care the effects of the flow rate increase over the next 24 hours or so.

http://www.nikkei.com/news/headline...19695E2E5E2E3E38DE2E5E2E0E0E2E3E0E2E2E2E2E2E2 :
7 February 08:00 : 71.4°C
7 February 10:00 : 69°C

http://www.nikkei.com/news/headline...19695E2E5E2E6948DE2E5E2E0E0E2E3E09180EAE2E2E2 :
7 February 13:00 : 71.5°C
No xenon was detected on 7 February.

http://sankei.jp.msn.com/science/news/120207/scn12020714230004-n1.htm
7 February 17:00 : 68.5°C (and the other two thermometers have dropped to around 41°C)

http://www.tokyo-np.co.jp/article/national/news/CK2012020702000039.html The core spray system had been interrupted for 6 hours on 26 January in order to change a pump. Tepco says the way the water is flowing might have changed at that time, no longer reaching the areas close to the fuel as well as before. Institute of Applied Energy department head Masanori Naito said some fuel might have fallen into the RPV bottom and formed a small heap.

http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_120207_06-e.pdf Diagram showing the 3 thermometers located at 0°, 135° and 270° of angle. The hot one is the one located at 0° on the mountain side.

 

[dezzert]

Truth is, for some people whatever they do, they do wrong.

If they add boric acid, it means they are adding it because they know there is a recriticality, they just doesn't tell anyone. If they don't add boric acid, why the hell they don't add this if there is an obvious recriticality? It is their fault both ways.

No, actually the truth is if you post a pro-nuclear non technical blurb on this forum its OK, but an anti-nuclear non technical blurb is instantly removed.

And you can delete me from this forum cause it doesn't really deal with technical issues, only what Tepco feeds you. There are incredibly important technical issues that this forum avoids. Unless of course its a pro nuclear view.

Brilliant

 

[Cire]

No, actually the truth is if you post a pro-nuclear non technical blurb on this forum its OK, but an anti-nuclear non technical blurb is instantly removed.

And you can delete me from this forum cause it doesn't really deal with technical issues, only what Tepco feeds you. There are incredibly important technical issues that this forum avoids. Unless of course its a pro nuclear view.

Brilliant

To directly address your question (was there one?). I've found this forum to be moderated quite well. This topic for the most part remains technical and a great source of information on the state of the plants.

For or against the use of nuclear power really isn't relevant to the discussion here is it?

 

[etudiant]

No, actually the truth is if you post a pro-nuclear non technical blurb on this forum its OK, but an anti-nuclear non technical blurb is instantly removed.

And you can delete me from this forum cause it doesn't really deal with technical issues, only what Tepco feeds you. There are incredibly important technical issues that this forum avoids. Unless of course its a pro nuclear view.

Brilliant

I do not think your comment about the scope of this forum being restricted to the TEPCO data releases is at all correct. Nor have I seen the kind of selective message purging you suggest.
It would be more helpful to list the top technical issues that you believe this forum refuses to discuss.

 

[nikkkom]

No, actually the truth is if you post a pro-nuclear non technical blurb on this forum its OK, but an anti-nuclear non technical blurb is instantly removed.

And you can delete me from this forum cause it doesn't really deal with technical issues, only what Tepco feeds you. There are incredibly important technical issues that this forum avoids. Unless of course its a pro nuclear view.

I am at times rather harsh towards nuclear industry. And I did post quite a number of my thoughts here. Even though this did upset a few pro-nuclear people, I was not banned and my posts were not deleted.